Telephoste-exchastge



u. E. 14012313051; PARYY LINE TELEPHONE EXCHANGE. APPLICATION FILEDMAR/0. 9i RENEWED APR. 22. $918.

- 2 SHEiTS-SHEET I.

Patented D66. 3

E. NORSTRUM.

PARTY LINE TELEPHONE EXCHANGE. APPLlCATlON FILED mmzo, 1910. 1,326,212.

RENEWED APR. 22. I938- P'umwa 1m. 30,1919.

2 SHEETSSHEET 2.'

.NN N MEN war.

STATE s PATENT onnion.

ITILSEMEL NORSTROM, OF CHICAGO, ILLINOIS.

Specification of Letters Patent.

PARTY-LINE TELEPHONE-EXCHANGE.

Application tiled March 20,- 1916, Serial No. 85,279. Renewed April 22,1918. Serial No. 229,938.

To all whom it may concern:

Be it known that I, NIL8 EMEIENORSTROM, a citizen of the United States"of America, and a resident of Chicago, county of Cook, and State ofIllinois, have'invcnted certain new and useful Improvements in Party-Line Telephone-Exchanges, of which the following is a specification.

My invention relates to party line telephone exchanges, and has for itsobject improvements in such exchanges.

In the accompanying drawings Figure l is a transverse section of a cen-I tral oflice keyboard suitable for operation in this exchange, only somuch of said device being .shownas-js deemed necessary to explain theoperations of the exchange;

' Fig. 2is an enlarged plan of part of the contact arms shown in Fig. 1;

. Fig. 3 is a side elevation of three of thecontact arms shown in Figs.1 and 2;-

Figs. 4 and 5 are section and perspective,

" of the drawing, and lines leading to other local stations at the lower'left hand corner.

The keyboard, or calling device, shown in F i 1 consists of a suitableframe hav ing tw rows of insulated keys 10 which are properly numberedto represent different stations on a party line. There is presumed to beone such keyboard at each operators position in' the exchange, but thedia ram illustrates connections to only one of t em.

Beneath each row of keys 10 is a shaft 11 on which are loosely mountedcontact arms 114, there being one such arm for each key 10. Associatedwith eacharm'114 is a collar 12 secured to the shaft 11 by set screw 13.A spring 14 on each-collar serves to nor mally depress the inner end ofthe associated arm 114. On the lower end of the stem for each key 10 isa head 15 which, when the keys 10 are in elevated position as shown inFig. 1, engages the upper end of associated arm'114 to push it outwardand consequently to raise the inner end. When, however, a key 10 isdepressed, the spring 14 connected to the corresponding arm 114 movesthe inner end of the arm downward Patented Dec. 30, 1919.

andthe upper end inward so that the man, 16 dropsover the head 15 andholds the key" depressed until released as hereinafter do.

scribed.

In the. center of the calling device is a.

shaft 150 on which are spirally arranged? a series of wiper arms 115.These wiper arms consist of sheet metal 17 formed around blocks 18 heldto shaft 150 by set screws 19. These wiper arms have the outer on shaft150 so that each wiper arm may engage two, contact arms 114 as shown inFig. 2. Each block 18 has its outer end cut away as shown at 20 so thatthe wiper arm will .make electrical connection with a contact end of thesheet metal. 17 curved as shown" a. i

in Fig. 5, and are arranged longitudinally" 7 As the shaft 150 advancesstep by step, i

a wiper 115 first engages a contact arm 114,

' (if it is at the time in a depressed position), v and then pushes theinner end of the arm upward to release the engaged head 15 and permitthe depressed key 10 to rise to normal position. As the wiper arms arespirally arranged on the shaft 150, it will be evidentthat the number ofsteps which the shaft makes before a key is released will depend uponwhat key 10 is depressed.

The switching mechanisms at the local stations are of an ordinary andwell lmown kind, and do not need description. However, there is acharacteristic of such switching mechanism which calls for specialnotice because it has a bearing upon the operation 'at the centraloflice. The matter referred to is illustrated in Fig. 6. The ratchetwheel 22 is mounted on the shaft 23 and is driven by a pawl 24. Adjacentto the wheel 22 are some contact springs, one of which carries a pieceof insulation which engages a fiat-- tened part of shaft 23. Theflattened part of the shaft acts as a cam to move the central springfrom electrical connection with.

the upper spring to electrical connection with the lower one. Theratchet wheel has fine teeth and is operated by impulses sent from thecentral office. Owing to the finemass? of the teeth, one step of theratchet wheel isnot enough to shift this connection with certaintyunless the adjustment of the spring is made with extreme care. Toovercome this difficulty in the ordinary local station switchingmechanism and to avoid such extreme delicacy of adjustment, the callingdevice at the central ofiice 'is made so that it will never send outless than a plurality of operating impulses, no matter-what station maybe called. 1

. impulse sender S driven by a motor genera-v tor MM, the current foroperating which comes from a battery X. This battery is the regularcentral energy storage battery used in common battery exchanges. Theimpulse sender distributes impulses from the generator part M as will bedescribed.

Also at the central office are a'generator 99, certain keys, magnets,contacts and connections, all of which will be understood from thedescription of the operation of the exchange.

It will be assumed that the subscriber at the local station shown in theupper right hand corner of Fig. 7 calls central,-and that the operatorresponds and makes the desired connection.

To call central, the subscriber turns the crank of his generator when acurrent flows: G 31;323334-35-36,373839 L041-4243.44-4546474819- 5O 51-GThis operates drop 38 to call operator,

who inserts plug in jack and presses listen ing key K, whereupon thetalking circuit between'calling subscriber and operator is as follows:receiver at local station S 52 hook53-54553F135-36 56plug and operatorsset4546 474849 5051-receiver.

To call another subscriber on the same party line, the operator pressesthe key 10 on her calling device which corresponds to the station to hecalled. She also presses key K. The completed circuit is :X-57" 58-59-606162-Coil A'63--ground X. Coil A shifts the contact springs aboveit to complete a'circuit for the motor M as follows :X56-5758-59-60616264.65-66-Mgr0und-X.

The motor M drives the l00-volt dynamo M and the impulse sender S. Fromthese impulses flour to operate magnets C and D, and the stepping upcoils at the local stations, and a corresponding stepping up deviceatthe central oflice. The first circuit i's":M 676869-70ground to thelocal stations on the linc71-7248- '474645-73 7=l 5 7 67 7 -78-7 9-There is also a branch to ground at central through magnet 87 and wire88 to-45 where it joins the previous circuit. The impulses in this caseare in the release direction through the stepping up magnets, the'object being to insure that all switching mechanisms at the localstations, and the corre sponding one 87 at the central office, shall bein normal position when stepping up impulses begin.

- The first impulse through magnet D closes 90 to 91, when a circiiit iscompleted as fol- 9'2groundX. Magnet B closes ground connection foritself at 93-94, so that it is independent of the connection closed byD,

and also closes for C a circuit as follows tion to engage an contactarms-114 w ich may have been cpressed by the operator pressing one-ormore of the keys 10. On the shaft 151 is a loose arm 162 located betweenand driven by twopins on the wheel 151. There is a little pla betweenthe arm 152 and the pins in the wheel so that two or more steps will bemade by the wheel before the adjacent pin thereon engages andmoves thearm 152 from its normal position., The arm 152 has, on its outer end, apiece of insulation on which rests the end of the spring 80 when the armis in normal position. When, however. the arm 152 has moved from underspring 80, electrical connection shifts from 81 to 98. In this conditiontherelease impulses previously described as passing from 80 to 82 by wayo'f.8l will thereafter pass by way of the resistance R. These releaseimpulses through resistance R continue, and alternating with them areoperat ing impulses as follows :M?67-68-69- 96--97988079., and so onover the same circuit". but in the. operating direction through magnets71 and 87. In other words, operating. impulses and release impulses flowalternately from the dynamo M through the ste ping up coils. Theoperating impulses are full strength, while the release impulses flowthrough the resistanceR and have only sufficient strength to neutralisethe residual magnetism in the coils and assist the reverse movement oftheir armatures.

During this operation, magnet C continues to receive operating impulseswhich are simultaneous with the release impulses through the stepping upcoils, but which pass around resistance R. These impulses through Cadvance shaft 150 and wipers 115 as before described. If we assume thatthe -key 10 on the keyboard which the operator iaq then, after thestepping up coils have made their ninth step, magnet C brings the tenthwiper 115 into electrical contact with the tenth contact lever 114. Thiselectrical connection remains while the stepping up coils make theirtenth step, immediately after which the next step by magnet C causes thetenth Wiper to push up the tenth contact lever 114 tobrealr theelectrical connection at this point and permit key 10 to rise.

At the local stations, each forward step. causes spring 32 to engagespring 106. and at station N0. 10 the tenth step cause; arm 118 to pushspring 104- into engagement with contact 103. When this occurs, itourrent fiows:-generator is at central-100- 63-ground to local stationNo. 10-cut-in coil lO1l02-103104-10510632r33 i3435-36--5 i-1O7--- 198109 110 1111l21 13-114 115 116117--99.

At the beginning of the stepping up movements at the local station, thecam on shaft 2?; moved spring ,50 from electrical connection with spring49 to connection with contact 134. A similar action also occurs forswitch 87 at the central olfice. At the differout local stations on theline, the arms 118 move spring 104 in succession, one at each step ofthe switching mechanisms. Consequently the nnpulse last described foroperating" the lock-in coil 101 goes only through the selected stationNo. 10. The operation'of this coil shifts the electrical connectionsjust above its armature and thereby connects the selectedstationtelephonically to the line.

The rise of key No. 10 on the calling device breaks the circuits, eitherdirectly or indirectly, for the magnets A, B and and the motor M. Theoperation of the-switch 87 at central, howeverpprovides anothercircuitas followst-X1.19120121-122 1:23l24125 -6(3-M-gro1xndX. T helampv 124" in this circuit provides resistance which permits the-motorto continue running, but atareduced speed.

hen the circuit. through magnet A is broken as described. the contactsprings moved thereby return to their normal position, whereupon acurrent flows :--99 "l0f}- 12e 12777- 7c-75- 74-73 r +c -4? scriber, andthe ringing continues as longas.

In the lower part of Fig. 7 is; shown a.

plug! l? adapted to be inserted in a jack J c-(l to another part line L.It will {al that with plug l in jock J an 2y on line L might he calledby the .r c j*:-.-.- il'=s(:ril ed. lVith both plugs in their ing-outdrop 138 to inform the operator that y the conversation is ended.

The operator removes plug from jack to permit 45 to close to 44, when acurrent flows:M -6768 (i9 70-ground to all local stations on thelineT1-7248-47 46 -45-4443-4241-14-2143 144 82Q384,85-86 M There is alsoa branch through 87 to 44. These impulses are, at filst, of low voltage,due to the slow running of the motor as before described. The armatureof switch 87, however, isarranged to have play between stiff springs sothat the low voltage from M may move the armature far enough to closecontact 145. This closure shunts the lamp 124 so that the motor may getfull voltage from battery X. This permits the motor to ingiven circuit,which impulses are in the release direction. The central office switch87 is provided with an unusually heavy ratchet wheel, or other heavymoving parts, so that it will be more sluggish in its release actionthan are theswitches at the local stations. This permits the switches atthe local stations to return to normal position sooner than switch 87.Upon release of switch 87, the motor circuitis broken at 121-122, andthe motor 'stops. The same release also bridges the drop 38 by closingcontacts 40---l1. The contacts 40-41are used to cut the drop 38 from theline so that contact 44 may he used to carry release impulses uponremoval of the plug without causing the drop 38 to flutter. f When acall is made on a party line, all stations on the line have theirsprings 50 moved from contact 49 to contact 134. At the called station,the lock-in coil-10l-has been operated. At uncalled stations thecontacts operated by this coil are in their normal position. If anuncalled subscriber attempts to call central when the. line 15 busy, hisgenerator will be shunted as fol lows :-G 313Q3355-54 53;-145133134--'5O-51.G If. however, the subscriber should press his emergencykey 54, the shunt would be cut out and the circuit would be through theclearing out drop 138 as given for ringing off, except last part whichis I47l48t-1601615i-53l45 133-13i 50-51--G It will be observed that theshunt just given for the magneto or generator (al con- .tainsnoresistance when the line is busyv emergency button not pressed. Underthese circumstances no current would flow, and the difference between nocurrent and the small amount necessary to call central is not enough toindicate by feeling that the line is busy.

At the upper part of that portion of the drawing which shows the localstation are two binding posts-300, and farther down on the drawing arefour binding posts 301. .The apparatus included between binding posts300 and; binding posts 301 is thc lockiut apparatus, and is inclosed ina locked and sealed case or box.- The apparatus below binding )osts 301is that contained in the ordinary telephone box. The party lineconnections are made at posts 300, and posts 300 and 301 are secured tothe ease containing the lock-out apparatus.

Emergency keys, such as 54, have heretofore been used in party lineexchanges, and to prevent an uncalled subscriber from listening in onthe line by pressing this button, there has been provided a shunt forthe receiver. This shunt has, heretofore. always been one of the exposedwires extending from the case containing the look-out apparatus to thetelephone box. As this wire served nopurpose other than that of shuntingthe receiver in an uncalled station, it was always possible to releaseit from one of its binding posts without disturbing the operation of theapparatus or giving any appearance of change. By so doing an uncalledsubscriber could press his emergency key and listen on the line. Thereason .why this has heretofore been possible is that 'the emergency keywas placed on the same side of the line as the contacts operated by thecut-in-coil, (open at all uncalled stations), and was used to close:the' circuit around those contacts to enable the subscriber to send amagneto current to central. Prevention for listening was due solely tothe shunt which a subscriber might releaseor cut because exposed.

In the present case I have removed the emergency key to the other sideof the line so that it does not close the circuit around the contactsoperated by the cut-in coil, and use part of the talking shunt as partof the magneto'circuit for calling central. This talking shunt in anuncalled station is: Re ceiver S- 52 -531l5133-13-l50 5l-receiver.Cutting the. shunt connection 115 would cripple the connection foremergency calling without enabling the uncalled subscriber toflisten onthe line because the emergency key does not close around the openconnections. Consequently lmay place this shunt 145 in either an exposedor an unexposed position withoutaffording means by which an uncalledsubscriber may listen on the line. I have, however, placed it entirelywithin the sealed box containing the lock-out. apparatus. whichheretofore could not be done.

Returning now to the impulse sender b, it will be seen that this is adevice for supplying or sending alternating impulses to ground, and forseparating the impulses so that plus impulses are sent over one line Iand minus impulses over another line. Thus, if we consider impulses asflowing from the sender, positive impulses would flow from the brush 96,and negative impulses from brush 83. One keyboard having keys 10 and 10is shown as connected to the brushes and 83, and to the battery X. l twill be evident that the inipulses flowing from the sender andcontrolled by the kerboai'd are not influenced by the presence orabsenceof another keyboard connected to brushes 96 and 83, and battery X.Consequently, other keyboards with their associated parts may beconnected to the same brushes and calls may he made simultaneously overother lines without causing confusion. Connections completed are shownfor one 'keyboard,-and other connections are shown at 302 which may beextended in the'. same way to another keyboard. In the construction andarrangement shown, one impulse senders, and one stepping impulses mayflow over one line and simultaneously therewith release impulses mayflow. over another lineal] impulses coming from one and the same sender.The, keyboard also governs the flow ofimpulses over the line so thatrelease impulses of reducedstrength will alternate with the fullstrength stepping impulses.

In calling over two lines at the same time,

esser-.2

vplugs 73 -107 and P are inserted in the oi the respective lines, andthe lreys ii?- and K are In this condition step-- ping up coils of bothlines are connected toetlier throu h the tip sides of both oluus i" 1. a7

line through the wires lb. Consequently, each impulse operates over bothlines to produce simultaneous operation of the stepping up coils on bothlines. Heretotore, when calls were made over two lines, impulses weresent alternately, first over one line and then over the other. Thepresent arrange- .ment which connects the two lines as describedsaves intime required for calling and also in equipment.

' While pressing both lreys K and K connects the tip sides of plugstogether, that action separates the sleeve sides. By referring back tothe circuit from generator through the cut-incoil 101 it will be seenthat that circuit goes through the sleeve side 107 and the contact arm114: controlled by similar circuit may be traced from the 0. other sothat" a contact made by one wiper the key 10 on the keyboard. Aprecisely sleeve side of plug P to the contact arm 114. on the oppositeside of the calling de vice. The contact arms 114. on one side and 11 onthe other-are insulated from each "115 to send out an .impulse through.the sleeve side of one plug does not necessarily involve a similarimpulse through the other plug. If th contact arms are d rectly oppositeeach other, then the w1per 115 will connect to both at the same time andcut-in impulses will flow over both lines at once. If,

however, the contact arms 11% and 114" which are depressed are atdifferent longs. tudinal positions in the calling device, then they willbe operated by different wipers 115.

5. What I claim is:

1. A source of alternating impulses, a. party line over which suchimpulses may flow, a calling device arranged to control the distributionof the impulses to the line, and means for controlling the callingdevice by theimpulsesu I 2. A source of alternating impulses, a partyline, a calling devicarranged to distribute the impulses from source ina' and the impulses from the sender .6 come to center of tlns connected-.stations on both lines.

predcterminied arrangement to the party line, and means for operatingthe calling device by the impulses.

3. A battery, a motor-generator driven thereby, a calling deviceoperated by impulses from the motor-generator, and means by which thecalling device controls the number and distribution of impulses from.the motor-generator.

4:. A battery, a motor-generator driven thereby, a circuit over which acurrent may flow from the generator, a commutator driven by the motor.and serving to transform the current from the generator into alternatingimpulses flowing over the line, and nieans'controlled by thecommutatorfor re-' ducing the voltage ,of each. alternate impulse.

5. A battery, a motor-generator driven thereby, a calling device, acircuit over which impulses from the motor-generator operate the callingdevice, a party line arranged to receive impulses'from themotorgenerator, and means by which the calling device controls theimpulses to itself and to the party line. 4

6. The combination with two p'arty lines.

eachhaving .a plurality oflocal stations thereon and each station havinga step-bystep mechanismconnected to the line, and

a cord connecting the .two lines, of a source of electricity connectedto one side'of the cord, and means by. which impulses from said sourceare caused to flow over both lines simultaneously to cause allstep-by-step mechanisms of both lines to move in-sync chronism; v

7 The combination with ously connected to bothlines, of a wire connectedto the connecting side of the cord, 9. source of electricity, and meansby which impulses from said source are caused to flow over said wireancord to cause simultaneous operation or, ectrical apparatus at all 8.Two party lines'each having local stations with step by-stepapparatusthereat, a central ofiice to which said lines are connected, an impulsesender at said office, and means by which each impulse from said sendercauses'the same operation of the step-by-step apparatus of all"stations. of both lines.

9. The combinationiwith twoparty lines,

an impulse sendenjafcalling device control- I hug the impulses from saidsender, anda.

generator, ofa cord serving to connect the two lines, means by whichones1de of sald I cord connects corresponding branches of the two linestogether so that impuls'esirom said' sender will flow alike ove1.'theconnected branches, and means by whichtlieother-side two party lines,"and a cord having the same -side simultaneof saidcord' separatesthebther branches of the two lines soth'atimpulsesimm said generatorwill flow at different times over the separated branches.

a source of. alternating impulses, and a calling device for distributingsuch impulses in a predetermined manner to said lines, of a cordprovided with means for connecting together corresponding branches ofeach line and separating other branches, connections from the callingdevice to one branch of the cord so that given impulses will flowsimultaneouslyIover the connected branches, and other connections fromthe calling device to the other branch of the cord so that impulses willflow at different times over the separated branches.

v11. A party line terminating in a jack in a central ofiice, switchingmechanisms at local stations on the party line, a special switchingmechanism at the central ioflice and also connected to the party line, aline drop at the central ofiice and operable from the stations on theline, means by which upon insertion of a plug in saidjack operatingimpulses may be sent to all of said switching mechanisms, means by whichrelease impulses are automatically sent to all switches upon removal ofthe plug from the jack, and a connection for said drop controlled by thespecial switching mechanism so thatthe said drop has its circuit brokenduring the sending of such release impulses.

12. The combination with a party line provided with a jack in which aplug may be inserted and removed, and a line drop operable from localstations on the line, of means for sending impulses over the line whenthe plug is not in the jack, and means by which such impulses areprevented from affecting the line drop.

13. A plurality of party lines extendlng to a central ofiice, a sourceof alternating ims,

pulses at the central ofiice, said source being provided withconnections to a plurality of. calling devices, a calling deviceattached to: a pair of such connect1ons,'a cord connecting the callingdevice to one of the party lines,

and means by which the impulses recelved by the calling device aremodified and distributed to the line to which it is connectedindependently of the manner in which the same impulses are modified. anddistributed to some other line connected to some other calling 'device'14. A party line.'switches connected to the party line and advanced byimpulses in one direction and released by impulses in the otherdirection. a source of alternating impulses, means by which uponconnecting said sonrceto'thc line impulses of full voltage in therelease direction will flow through said switches, and means by whichupon the'completion of a small number of such impulses a resistance willbe automatically placed in 10. The combination with two party lines,

the circuit for such impulses and other im pulses of full voltage in theoperating direction will alternate with the reduced impulses in therelease direction.

15. A party line, a source of alternating impulses, means by which uponconnecting the line to the source impulses in one direction will flowover theline, and automatirally operating means for inserting resistancebetween the source and the line upon the completion of a predeterminednumber of impulses.

16. The combination with a party line, and means for sending electricalimpulses thereover, of means controlled by the impulses for reducing thevoltage of all impulses following a predetermined number of impulses.

17. A central office, a party line connected to the central ofiice andhaving lock-out apparatus and a receiver at eachone of a plurality oflocal stations on the line, a connection at each local station servingto shunt the receivers at stations locked out, a genorator at each localstation,a signal at the central oflice adapted to be operated by thegenerator, and a manually closable circuit for said generator andsignal, said circuit being composed in part of the shunt for thereceiver at the same station.

18. In a lock-out'party line system. hav- .ing a central oflice and aplurality of local stations on& a party line connected thereto, a"telephonic shunt for each station locked out, a generator at each localstation, and a manually operated emergency connection for completing asignaling circuit from a locked out station to the central office, saidcircuit being composed in part of the telephonic shunt for the station.

19. In the local station circuits of a party .lme system, binding posts300 serving as connections between the line and the local station, otherbinding posts 301 serving as connections to the normal local stationtelephone apparatus, and a telephonic shunt for the station consistingof a connection lo cated between posts 300 and 301.

20. A party line terminating in a jack in a central office, switchingmechanisms at local stations on the party line and advanced by impulsesin one direction and released by impulses in the other direction, aspecial switching mechanism at the central office and also connected tothe party line, a source of, electrical impulses for op'erating all ofsa d mechanisms, and automatically operatmg means by which all impulsesflowing from said source over the line will be in release direction whenthe jack has no plug therein.

21. A party line. terminating in a jack at a central oiiice, switchingmechanisms at local stations on the party line and admadam 7.

vanced by impulses in one direction and released by impulses in theother direction, a special switching mechanism at the central oflice-andalso connected to the party line, a source of electrical impulses foropcrating all of said mechanisms, and means by which upon said specialmechanism l)('- ing advanced from its normal position when the jack hasno plug therein impulses from said source in release direction will heantomatically sent over the line.

' 22. A'p'arty line connected to a central office, switching mechanismsat local stacuit without affecting the shunt for the talking circuit.

23. A party line connected to a central otlicc, connections at eachstation on the line for establishing magneto and talking circuits forthe station, means controlled from the central ollicc for establishing aseparate shunt for each circuit, means under the control of a subscriberfor cutting the magneto shunt at his station, and means. under theexclusive control, of an operator at the cen traloflice for cutting thetalking shunt.

24. A party line connected to a central ofiicc. a nmgncto at eachstation on the line left means f which the subscriber thereat may callthe central ofiice, and means controlled from Ihc central otfice forconnecting 'a selected station telephoiiically to the line and for'establishing a shunt at each other local station for the magnetothereat, said shunts having no resistance therein other than thatexisting in the connections forming them.

Signed at Chicago, 111., this 18th day of March, 1916.

NILS EMEL NORSTROM.

